The high-field polar RX J1007.5-2017

We report optical and X-ray observations of the high-field polar RXJ1007.5-2017 performed between 1990 and 2012. It has an orbital period of 208.60 min determined from the ellipsoidal modulation of the secondary star in an extended low state. The spectral flux of the dM3- secondary star yields a distance of 790+-105 pc. At low accretion levels, \RX{} exhibits pronounced cyclotron emission lines. The second and third harmonic fall in the optical regime and yield a field strength in the accretion spot of 94 MG. The source is highly variable on a year-to-year basis and was encountered at visual magnitudes between V \sim 20 and V \sim 16. In the intermediate state of 1992 and 2000, the soft X-ray luminosity exceeds the sum of the luminosities of the cyclotron source, the hard X-ray source, and the accretion stream by an order of magnitude. An X-ray high state, corresponding to the brightest optical level, has apparently not been observed so far.Comment: To be published in A&

A new clue to the transition mechanism between optical high and low states of the supersoft X-ray source RX J0513.9-6951, implied from the recurrent nova CI Aquilae 2000 outburst model

We have found a new clue to the transition mechanism between optical high/X-ray off and optical low/X-ray on states of the LMC supersoft X-ray source RX J0513.9-6951. A sharp ~1 mag drop is common to the CI Aql 2000 outburst. These drops are naturally attributed to cessation of optically thick winds on white dwarfs. A detailed light-curve analysis of CI Aql indicates that the size of a disk drastically shrinks when the wind stops. This causes ~1-2 mag drop in the optical light curve. In RX J0513.9-6951, the same mechanism reproduces sharp ~1 mag drop from optical high to low states. We predict this mechanism also works on the transition from low to high states. Interaction between the wind and the companion star attenuates the mass transfer and drives full cycles of low and high states.Comment: 9 pages including 5 figures, to appear in the Astrophysical Journa

Supersoft X-ray sources in M31: II. ROSAT-detected supersoft sources in the ROSAT, Chandra and XMM eras

We have performed Chandra observations during the past 3 years of 5 of the M31 supersoft X-ray sources (SSS) discovered with ROSAT. Surprisingly, only one of these sources has been detected, despite a predicted detection of about 20-80 counts. This has motivated a thorough check of the ROSAT M31 survey I data, including a relaxation of the hardness ratio requirement used to select SSS. This increases the number of SSS identified in survey I by 7. We then carried out a comparison with the ROSAT M31 survey II dataset which had hitherto not been explicitly investigated for SSS. We find that most of the ROSAT survey I sources are not detected, and only two new SSS are identified. The low detection rate in the ROSAT survey II and our Chandra observations implies that the variability time scale of SSS is a few months. If the majority of these sources are close-binary SSS with shell hydrogen burning, it further implies that half of these sources predominantly experience large mass transfer rates.Comment: accepted for publ. in ApJ; 2 ps-figures; high-quality figures available at http://www.mpe.mpg.de/~jcg/publis.htm

Mapping the porcine RN gene to chromosome 15

International audienc

Exploring the Case for Expanded Remote Texter Liability for Employers

In 2013, the New Jersey Appellate Court decided the potentially landmark case of Kubert v. Best, recognizing for the first time that a sender of a text may be held liable to an innocent third party injured in an automobile accident caused by a driver who was distracted by receiving the text. Other subsequent cases have both confirmed and limited the Kubert ruling. In this article, we explore possible further extensions of the Kubert ruling, anticipating that because of expanding employer liability for acts undertaken by their employees, the next step in the evolution of texting and driving law may likely hold employers liable for accidents caused by their employees whose employment-related texts to others result in accident and harm

Applying Indices Post-\u3ci\u3eGrutter\u3c/i\u3e to Monitor Progress Toward Attaining a Diverse Student Body

The Supreme Court decision in Grutter v. Bollinger provided more definitive guidance for institutions of higher education desiring to use racial preferences in an effort to achieve a diverse student body. This Article first examines Grutter and other relevant cases to set forth the parameters established by the Supreme Court concerning how university preferences, including but not limited to race, may be used in an admissions policy. This Article then provides a framework for creating and using diversity indices that can help institutions implement the guidelines found in these court decisions and monitor whether or not the goal of diversity has been met. The Article describes a hypothetical situation, illustrating how diversity indices can be used in a manner that conforms to the admissions policy parameters established by the Supreme Court

Applying Indices Post-\u3ci\u3eGrutter\u3c/i\u3e to Monitor Progress Toward Attaining a Diverse Student Body

The Supreme Court decision in Grutter v. Bollinger provided more definitive guidance for institutions of higher education desiring to use racial preferences in an effort to achieve a diverse student body. This Article first examines Grutter and other relevant cases to set forth the parameters established by the Supreme Court concerning how university preferences, including but not limited to race, may be used in an admissions policy. This Article then provides a framework for creating and using diversity indices that can help institutions implement the guidelines found in these court decisions and monitor whether or not the goal of diversity has been met. The Article describes a hypothetical situation, illustrating how diversity indices can be used in a manner that conforms to the admissions policy parameters established by the Supreme Court

An optimum time-stepping scheme for N-body simulations

We present a new time-stepping criterion for N-body simulations that is based on the true dynamical time of a particle. This allows us to follow the orbits of particles correctly in all environments since it has better adaptivity than previous time-stepping criteria used in N-body simulations. Furthermore, it requires far fewer force evaluations in low density regions of the simulation and has no dependence on artificial parameters such as, for example, the softening length. This can be orders of magnitude faster than conventional ad-hoc methods that employ combinations of acceleration and softening and is ideally suited for hard problems, such as obtaining the correct dynamics in the very central regions of dark matter haloes. We also derive an eccentricity correction for a general leapfrog integration scheme that can follow gravitational scattering events for orbits with eccentricity e -> 1 with high precision. These new approaches allow us to study a range of problems in collisionless and collisional dynamics from few body problems to cosmological structure formation. We present tests of the time-stepping scheme in N-body simulations of 2-body orbits with eccentricity e -> 1 (elliptic and hyperbolic), equilibrium haloes and a hierarchical cosmological structure formation run.Comment: 15 pages, 10 figures, replaced with version that matches published versio